Pen



FIG. 1 is a left side view of a pen, wherein the tip of the pen is retracted;

FIG. 2 is a right side view thereof, wherein the tip of the pen is extended;

FIG. 3 is a top view thereof, wherein the tip of the pen is retracted;

FIG. 4 is a bottom view thereof, wherein the tip of the pen is retracted;

FIG. 5 is a rear view thereof, wherein the tip of the pen is retracted; and,

FIG. 6 is a front view thereof, wherein the tip of the pen is retracted.

The broken lines in the Figures show portions of the pen which form no part of the claimed design. 

CLAIM I claim the ornamental design for a pen, as shown and described. 